1. Technological objective
Clean coal technology-related development solely focused on a single industry in pursuit of a single product is reaching its limits in terms of efficiency and economy. This is necessitating the development of innovative technologies that could completely revolutionize energy and material production.
Efficient Co-production with Coal Flash Partial Hydropyrolysis Technology (ECOPRO) is a technology that causes pulverized coal to react rapidly under high pressure (2-3MPa) and in a moderate hydrogen atmosphere to highly efficiently obtain, from one reactor, synthetic gas that can easily be converted for use such as in integrated gasification combined-cycle (IGCC) power generation, indirect liquefaction (GTL), and chemicals, while co- producing light oil for utilization as a feedstock for chemicals and fuel.
The realization of a coal-based cross-industrial composite project, led by the electric power, chemical, and steel industries, with this technology as its core will hopefully bring a dramatic improvement to total energy utilization efficiency.
2. Technology overview
Figure 1 shows the total process flow of this technology. At the partial oxidation section of a coal flash partial hydropyrolsyis reactor, pulverized coal and recycled char are gasified with oxygen and steam at a pressure of 2-3MPa and at a temperature of 1,500- 1,600°C to give hot gas mainly composed of CO and H2. At the reforming section directly connected through a throat to the partial oxidation section, pulverized coal is injected together with recycled H2 into the hot gas stream from the partial oxidation section to complete the reforming reaction (partial hydropyrolysis) instantly under the condition of 2-3MPa in pressure, 700-900°C in temperature, and approximately 30-50% in hydrogen concentration (H2 in hot gas and recycle H2 combined). At that time, hot gas from the partial oxidation section also functions as a source of the reaction heat required at the reforming section. At the reforming section, a hydrogenation reaction adds H2 to primary pyrolysis, such as tar released from pulverized coal, changing heavy tar-like matter to light oil.
The gas, light oil, and char produced at the partial hydropyrolysis reactor follow a process where, after char separation at the cyclone and subsequent sensible heat recovery, synthetic gas (syngas) should be formed by way of oil recovery, desulfurization, and other gas purification processes. A portion of the syngas is converted into H2-rich gas, in the course of a shift reaction and decarbonization (CO2 recovery). After pre-heated via a heat exchange, the gas is recycled to the partial hydropyrolysis reactor’s reforming section.
The final syngas product is characterized by its main composition of H2, CO, and CH4 as well as hydrogen-rich contents of H2/CO 1 and is used as a source gas for IGCC, GTL, and chemicals. Light oil is mainly composed of aromatic compounds with 1-2 rings such as benzene and naphthalene, which have applications for chemical manufacturing or fuel for power generation.
The gas, light oil, and char produced at the partial hydropyrolysis reactor follow a process where, after char separation at the cyclone and subsequent sensible heat recovery, synthetic gas (syngas) should be formed by way of oil recovery, desulfurization, and other gas purification processes. A portion of the syngas is converted into H2-rich gas, in the course of a shift reaction and decarbonization (CO2 recovery). After pre-heated via a heat exchange, the gas is recycled to the partial hydropyrolysis reactor’s reforming section.
The final syngas product is characterized by its main composition of H2, CO, and CH4 as well as hydrogen-rich contents of H2/CO 1 and is used as a source gas for IGCC, GTL, and chemicals. Light oil is mainly composed of aromatic compounds with 1-2 rings such as benzene and naphthalene, which have applications for chemical manufacturing or fuel for power generation.
The features of this technology include:
- High-efficiency: The sensible heat of hot gas generated at the partial oxidation section is effectively used as a source of heat required at the reforming section, providing high energy conversion efficiency.
- Flexible productivity: The reforming section temperature, as well as the amount of hydrogen injected, can be controlled, allowing the freedom to change the gas/oil composition and output ratio, thereby flexibly responding to consumers’ needs.
- Economy: The cost of producing syngas can be partially offset by the value of the of co-produced high-value-added oil.
3. Progress and development results
1) Basic partial hydropyrolysis test (1996-1999, 1kg/day)
Using a small-scale test unit, the pyrolysis behavior of coal under the target conditions of this technology was reviewed, confirming that the hydropyrolysis of the primary tar released from the flash heating/pyrolysis reaction of coal was successful.
2) Process development unit (PDU) test (2000-2003, 1t/day Nippon Steel Engineering Co., Ltd. in-house research)
Using a reforming/partial oxidation-integrated PDU test unit, the basic performance of a partial hydropyrolysis reactor as the core of this technology was evaluated, clarifying the reaction in the reactor.
3) Pilot plant test (2003-2008, 20t/day)
Tests are being conducted using a pilot plant with a thermally self-supportable reactor combined with other ancillary process units to enable forecasts for a future demonstration unit (up to 1,000t/day).
References
1) H. Shimoda et al., 10th Annual Conference on Clean Coal Technology lecture collection, p. 296, 2000.
2) H. Yabe et al., 2nd Japan-Australia Coal Research Workshop Proceedings, p. 257, 2002.
Source: New Energy and Industrial Technology Development Organization (NEDO), Japan Coal Energy Center (JCOAL)
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